The activated form of the human proto-oncogene c-Ha-ras (EJ or T24) that was cloned from a cell line established from a bladder carcinoma is capable of transforming NIH 3T3 cells in culture. The DNA sequences involved in the control of expression of this gene are being defined. The techniques of S1 mapping and primer extension will determine the 5 feet end of the processed transcript. To analyze the DNA sequences that constitute the promoter element, sequences 5 feet to the coding region of the gene will be cloned into a recombinant plasmid vector and assayed for their ability to initiate expression of a foreign gene by RNA and protein production in a transient assay system.